Tosefta sur Péa 6:2

Rebbi Ilai said, “I asked Rebbi Yehoshua, ‘Regarding which sheaves Bet Shammai and Bet Hillel argue [whether they are considered to be Shikcha (forgotten sheaves) or not]?’ He said to me, ‘[I swear] by this Torah [that they argue]’ regarding a sheaf [that is left in the field] next to a hedge, or [next to] a stack, [or next to] cattle [used for plowing], or [next to plowing] tools, and it was forgotten [there by the farmer].’ And when I came and asked Rebbi Eliezer, he said to me, ‘They agree by all of these [cases that Rebbi Yehoshua mentioned] that it is not [considered to be] Shikcha. [So] what [case] do they argue about? Regarding a sheaf that [the farmer] took [with him] to bring to the city and put it on the side of a stone fence or on the side of a hedge [in order to take a break], and forgot it [there], that Bet Shammai say that it is not [considered to be] Shikcha, because he [already] acquired it [for himself], and Bet Hillel say [that it is considered to be] Shikcha.’ And when I came and proclaimed [these] words [of Rebbi Eliezer] in front of Rebbi Elazar Ben Azaryah he said to me, ‘[I swear] by the Torah, these are the words that were spoken to Moshe on Sinai.’”